Reclosable Plastic Bags with Multiple Closures

ABSTRACT

A reclosable plastic bag, comprising front and rear panels formed of plastic film and sealed about their side and bottom edges to leave a top opening, each of the panels having an inner surface and an outer surface, first and second closures on the inner surfaces of each of the front and rear panels to close and open the top opening, wherein the first and second closures are parallel to one another and spaced apart at a distance from one another, and a thickened region on the outer surface of the front panel between the first and second closures.

FIELD

The present invention relates generally to reclosable plastic bags with multiple closures.

BACKGROUND

Reclosable plastic bags formed from a continuously extruded sheet of thin plastic are economical to produce. Bags with multiple closures, such as two closures that are generically and commonly referred to as “zip-lock” closures comprising interlockable rib and groove profiles, have the benefit of increased closure security, especially for air and water tightness.

Existing reclosable plastic bags with two zip-lock closures suffer several shortcomings. Market price pressure to reduce cost and minimise plastic usage by making the walls of the bags very thin and flimsy has adversely affected performance and functionality of the zip-lock closures during opening and closing.

During opening, the zip-lock closures often have a resistance to being opened that exceeds the strength of the very thin bag walls. As a result, the zip-lock closures frequently rip or tear away from the very thin bag walls. During closing, the very thin and flimsy bag walls make it difficult to align, press and close the two zip-lock closures.

A good design solution for reclosable plastic bags should offer an optimal trade-off that allows plastic usage and cost to be minimised by using very thin bag walls without decreasing performance or functionality of the zip-lock closures.

In view of this background, there is an unmet need for improved reclosable plastic bags with multiple closures.

It is a preferred object of embodiments of the present invention to at least partially address or ameliorate one or more of the above disadvantages, or at least provide a useful alternative.

SUMMARY

According to the present invention, there is provided a reclosable plastic bag, comprising:

-   -   front and rear panels formed of plastic film and sealed about         their side and bottom edges to leave a top opening, each of the         panels having an inner surface and an outer surface;     -   first and second closures on the inner surfaces of each of the         front and rear panels to close and open the top opening, wherein         the first and second closures are parallel to one another and         spaced apart at a distance from one another; and     -   a thickened region on the outer surface of the front panel         between the first and second closures.

The first closure may be between the second closure and the top opening.

The thickened region may be integrally formed by one or both of extrusion and embossing.

The embossing may comprise raised or impressed crosses or criss-crosses.

The thickened region may have a width that is 20% to 80% of the distance between the first and second closures.

The width of the thickened region may be 50% or 60% of the distance between the first and second closures.

The thickened region may have a thickness or height above the front panel that is greater than a wall thickness of the front and rear panels.

The thickened region may have a thickness or height above the outer surface of the front panel that is greater than or approximately equal to the thickness or height above the inner surface of the first and second closures.

The thickened region may have a stiffness or rigidity greater than the stiffness or rigidity of walls of the front and rear panels.

The first and second closures may comprise first and second zip-lock closures.

Each of the first and second zip-lock closures may comprise interlockable rib and groove profiles.

The first zip-lock closure may comprise a rib profile on the inner surface of the front panel and a groove profile on the inner surface of the rear panel, and the second zip-lock closure may comprise a groove profile on the inner surface of the front panel and a rib profile on the inner surface of the rear panel.

The rib and groove profiles may be configured to generate an audible clicking sound when interlocking to close the first and second zip-lock closures.

The thickened region may be integrally extruded with the front and rear panels, and the first and second zip-lock closures.

In use, the thickened region may increase ease of opening and closing the first and second zip-lock closures.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which:

FIG. 1 is a schematic front view of a reclosable plastic bag having two zip-lock closures according to an embodiment of the present invention;

FIG. 2 is a detail cross section view of the two zip-lock closures of the reclosable plastic bag;

FIG. 3 is a magnified cross section photograph of the two zip-lock closures of an example of a reclosable plastic bag; and

FIG. 4 is a side-by-side photograph of the example showing the front panel (left side) and rear panel (right side) of the reclosable plastic bag.

DESCRIPTION OF EMBODIMENTS

Referring to FIGS. 1 and 2 , a reclosable plastic bag 10 according to one embodiment of the present invention may generally comprise front and rear panels 12, 14 formed of thin plastic film and sealed about their side and bottom edges to leave a top opening 16. Each of the panels 12, 14 may have an inner surface and an outer surface.

Elongate first and second closures 18, 20 may be formed on or in the inner surfaces of each of the front and rear panels 12, 14 to close and open the top opening 16. The first closure 12 may be between the second closure 14 and the top opening 16. The first and second closures 12, 14 may be parallel to one another and spaced apart at a vertical distance (top to bottom) from one another. The top-to-bottom distance between the first and second closures 12, 14 may generally correspond to the width of a thumb and forefinger of an average user.

An elongate thickened region 22 may be integrally formed on or in the outer surface of the front panel 12 between the first and second closures 18, 20. Opposite external edges of the thickened region 22 may be slightly spaced apart from opposing internal edges of the first and second closures 18, 20. The thickened region 22 may have a lateral length (left side to right side) that extends laterally along most or all of the lateral length (side-to-side) of first and second closures 18, 20.

The thickened region may be integrally formed by one or both of extrusion and embossing 24. The embossing 24 may, for example, comprise raised or impressed crosses or criss-crosses.

The thickened region 22 may have a vertical width (top to bottom) that is 20% to 80% of the distance between the first and second closures 18, 20. For example, the top-to-bottom width of the thickened region 22 be 50% or 60% of the top-to-bottom distance between the first and second closures 18, 20.

The thickened region 22 may have a cross-sectional thickness or height (inner surface to outer surface) above the front panel 12 that is greater than a wall thickness or wall gauge of the front and rear panels 12, 14. In other words, the thickened region 22 is thicker than the thin plastic film walls which comprise the front and rear panels 12, 14. The thickened region 22 may have a thickness or height above the outer surface of the front panel 12 that is greater than or approximately equal to a thickness or height above the inner surface of the first and second closures 18, 20.

The thickened region 22 may also have a stiffness or rigidity greater than the stiffness or rigidity of walls of the front and rear panels 12, 14. The greater stiffness or flexural rigidity of the thickened region 22 may be conferred by one or both of extrusion and embossing.

The increased stiffness, rigidity, and strength of the thickened region 22 may be enhanced by the embossing process by strain hardening. The mechanical properties such as yield and tensile strength performance may be significantly increased. The embossing may be added after adding the thickness. Embossing and restoration techniques may be conducted to strengthen the plastic used to form the thickened region 22. Different cross-sectional thicknesses may be subjected to embossing and restoration at different sheet patterns and emboss height rigidity. Different embossing patterns, depths and thicknesses may be used on the thickened region 22 to produce different beneficial effects on closing, but overall increase ease of closure may be provided by the thickened region 22 compared to conventional bags with multiple closures having no thickened and/or embossed external regions.

Further or alternatively, the stiffness, rigidity, and strength of the thickened region 22 may be increased relative to the plastic film walls of the front and rear panels 12, 14 by varying the mechanical properties of the plastic resin, and/or selecting a different resin having increased stiffness, to form the thickened region 22. The increased stiffness, rigidity, and strength of the thickened region 22 may also avoid or minimise ripping or tearing the first and second closures 18, 20 away from the front and rear panels 12, 14 during opening.

The first and second closures 18, 20 may comprise respective first and second zip-lock closures 18, 20. Each of the first and second zip-lock closures 18, 20 may comprise interlockable male and female rib and groove profiles.

The first zip-lock closure 18 may comprise a rib profile on the inner surface of the front panel 12 and a groove profile on the inner surface of the rear panel 14, and the second zip-lock closure 20 may comprise a groove profile on the inner surface of the front panel 12 and a rib profile on the inner surface of the rear panel 14. The rib and groove profiles may be provided on the inner surfaces of the front and rear panels 12, 14 in different combinations, arrangements and orientations.

The male and female rib and groove profiles may be configured to generate an audible clicking sound when interlocking to close the first and second zip-lock closures 18, 20. The clicking sound may be provided by conventionally modifying the rib and groove profiles, such as modifying the shape and/or thickness of alternating segments or intermittent parts of the profiles, for example internal clicking teeth.

The rib and groove profiles of the first and second zip-lock closures 18, 20 on the front panel 12 may have a first colour, the thickened region 22 may have a second, different colour, and the rib and groove profiles of the first and second zip-lock closures 18, 20 on the rear panel 14 may have a third, different colour. For example, the first, second and third colours may be green, yellow, and blue, respectively. Some of the colours may collectively change upon closure to visually indicate sealing.

The thickened region 22 may be integrally extruded with the front and rear panels 12, 14, and the first and second zip-lock closures 18, 20. The rib and groove profiles may be formed through extrusion die inserts. Gaps may be added to the extrusion die to form the thickened region 22 between the first and second zip-lock closures 18, 20 so that the thickening occurs on the outer surface of the thin plastic film of the front panel 12.

Additional structural and functional features such as gripping lines or ribs, closure indicator, and colour-change seals, may be extruded into the walls of thin plastic film of the front and rear panels 12, 14. For example, ribs or lines may be formed between the first closure 18 and the top opening 16, and above and below the first and second zip-lock closures 18, 20. Different resins may be used, together with different plastic additives.

In use, the thickened region 22 may increase ease of opening and closing the first and second zip-lock closures 18, 20.

The following Example is intended to illustrate the invention. It is not intended to limit the scope of the invention.

Example

A reclosable plastic bag having two zip-lock closures was extruded with front and rear panels formed of very thin plastic film using conventional plastics material, and conventional plastic bag manufacturing machines operating at conventional manufacturing speeds. A conventional extrusion die was modified so that a thickened region was integrally extruded between the two zip-lock closures on the front panel only.

FIG. 3 is a magnified cross section photograph of the example. The thickened region was only formed on the front panel between the two zip-lock closures. FIG. 4 is a side-by-side photograph of the example showing the front panel (left side) and rear panel (right side) of the reclosable plastic bag. The rear panel was conventionally formed with two zip-lock closures having no thickened region between them.

In this example, the thickened region had a width of 60% of the distance between the two zip-lock closures. The thickened region also had a thickness or height above the outer surface of the front panel that was greater than or approximately equal to a thickness or height above the inner surface of the rib and groove profiles of the two zip-lock closures. After extrusion, the thickened region was embossed with criss-crosses that were slightly raised relative to the rest of the thickened region.

The example was tested by users repeatedly opening and closing the two zip-lock closures. A conventional reclosable plastic bag having comparably very thin bag walls with two zip-lock closures, but without a thickened region between them on the front panel, was also tested by the same users as a conventional comparator for comparison.

Surprisingly, the results of this comparative testing were that the example with the thickened region on the front panel between the two zip-lock closures was significantly easier to repeatedly open and close without ripping or tearing the very thin bag walls compared to the conventional comparator. The testers reported that the thickened region made it easier to align, press and positively close the two zip-lock closures using thumb and forefinger. The criss-cross embossing on the thickened region also gave a unique and pleasant tactile sensation during opening and closing of the two zip-lock closures.

The invention is not limited to the example that have just been given. In other words, those skilled in the art will appreciate that the example may be reproduced without difficulty, and with similar success, by substituting any of the generically or specifically described structural and functional features of the zip-lock closures and thickened region mentioned anywhere in this specification for those actually used in the preceding example.

Embodiments of the present invention provide reclosable plastic bags that are both generally and specifically useful for minimising plastic usage and cost by reducing overall bag weight and wall thickness by allowing very thin bag walls to be used without decreasing performance or functionality of two zip-lock closures.

Surprisingly, the thickened region of embodiments of the invention makes it significantly easier for users to open and close the two zip-lock closures even when the overall weight and overall plastic usage of the bag is significantly reduced compared to conventional reclosable plastic bags by using plastic film bag walls that are very much thinner and flimsier.

Embodiments of the present invention advantageously provide very lightweight double zip-lock closure plastic bags with pleasant tactile feel and easy closure even with very thin gauge plastic walls. The consumer experience is improved and cost is lower compared to regular double- and single-zipper bags because the thickened region adds closing force and tactile feel to the two thin zip-lock closures, and guides the closing process better than regular double zippers. Embossing of the thickened region between the two thin zippers increases grip, added closing force, and improved tactile feel.

Although embodiments of the present invention have been described above by way of example only in the context of reclosable plastic bags having only one thickened region between one pair of zip-lock closures on only one side or panel of the bag, it will be nevertheless appreciated that embodiments may be alternatively implemented with different combinations of any number of thickened regions between any number of pairs of zip-lock closures on one or both sides or panels of the bag. However, while such variations may be possible, they will nevertheless be suboptimal for reducing cost, and overall weight and overall plastic usage, of reclosable plastic bags.

For the purpose of this specification, the word “comprising” means “including but not limited to,” and the word “comprises” has a corresponding meaning.

Terms such as “first,” “second,” etc are used as labels for nouns that they precede, and do not imply any type of ordering (eg, spatial, temporal, logical, etc).

In addition, certain terminology may also be used in this specification for the purpose of reference only, and thus are not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, and “below” refer to directions in the drawings to which reference is made. Terms such as “front”, “rear”, “top”, “bottom,” “side,” “inner,” and “outer” describe the orientation or location or both of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words having similar meaning.

Various components may be described or claimed as “configured to” perform a task or tasks. In such contexts, “configured to” is used to connote structure by indicating that the components include structure that performs those task or tasks during operation. As such, the component can be said to be configured to perform the task even when the specified component is not currently operational (eg, is not active or in use).

Any reference to prior art is not an admission that the prior art is common general knowledge.

The above embodiments have been described by way of example only and modifications are possible within the scope of the claims that follow. 

1. A reclosable plastic bag, comprising: front and rear panels formed of plastic film and sealed about their side and bottom edges to leave a top opening, each of the panels having an inner surface and an outer surface; first and second closures on the inner surfaces of each of the front and rear panels to close and open the top opening, wherein the first and second closures are parallel to one another and spaced apart at a distance from one another; and a thickened region on the outer surface of the front panel between the first and second closures.
 2. The reclosable plastic bag of claim 1, wherein the first closure is between the second closure and the top opening.
 3. The reclosable plastic bag of claim 1, wherein the thickened region is formed by one or both of extrusion and embossing.
 4. The reclosable plastic bag of claim 3, wherein the embossing comprises raised or impressed crosses or criss-crosses.
 5. The reclosable plastic bag of claim 1, wherein the thickened region has a width that is 20% to 80% of the distance between the first and second closures.
 6. The reclosable plastic bag of claim 5, wherein the width of the thickened region is 50% or 60% of the distance between the first and second closures.
 7. The reclosable plastic bag of claim 1, wherein the thickened region has a thickness or height above the front panel that is greater than a wall thickness of the front and rear panels.
 8. The reclosable plastic bag of claim 7, wherein the thickened region has a thickness or height above the outer surface of the front panel that is greater than or approximately equal to the thickness or height above the inner surface of the first and second closures.
 9. The reclosable plastic bag of claim 1, wherein the thickened region has a stiffness or rigidity greater than the stiffness or rigidity of walls of the front and rear panels.
 10. The reclosable plastic bag of claim 1, wherein the first and second closures comprise first and second zip-lock closures.
 11. The reclosable plastic bag of claim 10, wherein each of the first and second zip-lock closures comprise interlockable rib and groove profiles.
 12. The reclosable plastic bag of claim 11, wherein the first zip-lock closure comprises a rib profile on the inner surface of the front panel and a groove profile on the inner surface of the rear panel, and the second zip-lock closure comprises a groove profile on the inner surface of the front panel and a rib profile on the inner surface of the rear panel.
 13. The reclosable plastic bag of claim 11, wherein the rib and groove profiles are configured to generate an audible clicking sound when interlocking to close the first and second zip-lock closures.
 14. The reclosable plastic bag of claim 3, wherein the thickened region is integrally extruded with the front and rear panels, and the first and second zip-lock closures.
 15. The reclosable plastic bag of claim 10, wherein, in use, the thickened region increases ease of opening and closing the first and second zip-lock closures. 